Disk-drive devices using various kinds of disks, such as optical disks, magneto-optical disks, and flexible magnetic-recording disks are known in the art. In particular, hard-disk drives (HDDs) are widely used as computer storage devices and are indispensable for contemporary computer systems. Moreover, the HDDs have found widespread use for video recording and reproducing equipment, car navigation systems, cellular phones, and similar devices, in addition to computers, due to their outstanding information storage capabilities.
A HDD transmits data to a host in response to a read command from the host within a specified time. In particular, HDDs for audio-visual (AV) devices read out data in a relatively short time. For good performance, AV equipment avoids interruptions in video and audio signals to prevent such interruptions from being perceived as an equipment failure. Therefore, minimizing delays in the transfer of read data provided by an HDD to a host, for example, a main controller of an AV device, is an area drawing much attention in research and development of HDD applications to AV equipment.